Autograph note to Hugo saying that if Hugo cannot see him now he will call another day to express his pleasure at working under Hugo's inspiration. (On the back of the letter is a very rough drawing in brown ink with "Paris dans la brume" written on it).
Erdan was a French journalist working for L'Evénement (1850-1). He had to leave France after the publication of La France Mystique (1855), which mocked the Church, and lived in Italy. Cf. his long biography in the Grand dictionnaire universel du XIXe siècle.